Cleaning Loss Sensor Arrangement for Combine Harvester

ABSTRACT

A harvesting vehicle including a cleaning section including a blower and at least one sieve. The sieve is configured to transport a layer comprising a mixture of grain kernels and residue material towards an exit edge of the sieve so that kernels fall through openings of the sieve and the residue remains on the sieve until it is ejected from the sieve by crossing the exit edge. The sieve may be subject to a grain loss, including a sieve-off loss and a blowout loss. The cleaning section further includes a sensor configured to determine whether the blowout loss or the sieve-off loss is a highest contributor to the grain loss. The cleaning section may also include a grain loss detector configured to measure the sieve-off loss and at least a portion of the blowout loss and a blowout sensor mounted above the sieve for measuring the blowout loss.

FIELD OF THE INVENTION

The present invention is related to agricultural harvesting vehicles,such as combine harvesters, for gathering and processing crop materialfrom a field, in particular to a harvester equipped with a sensorarrangement for monitoring losses of crop material in the cleaningsection of the harvester.

STATE OF THE ART

Combine harvesters are equipped with threshing/separation means arrangedfor threshing harvested crops and separating a mixture of grains andsmaller residue from the larger stalks and leaves of the crops, and witha cleaning section for further separating the grains from the residue.In many present day harvesters, the threshing and separation is done bya pair of longitudinally arranged threshing and separation rotors. Thecleaning section comprises preparation means, for example areciprocating grain pan, configured to deliver the grain/residue mixtureto a set of sieves, usually an upper and a lower sieve, which areequally moving in a reciprocating motion. Grains fall through thesieves, while residue is blown towards the rear of the machine by ablower or collected at the end of the sieves where it is evacuated fromthe harvester by a chopper/spreader arrangement. The cleaning section isusually mounted underneath the threshing rotors, i.e. between the frontwheels or tracks of the harvester.

An important factor in optimizing the throughput is the adequatemeasurement of parameters of the crop treatment process, in order to usethe measured values as inputs for various control loops applied in theharvester. One important parameter is the loss of the actual grainkernels in the cleaning section. These grain kernels (hereafter alsoreferred to simply as ‘grains’) are supposed to fall through the sievesas a mixture of grains and residue material passes through the cleaningsection. Nevertheless, a percentage of grains is lost due to two mainreasons: grains may become airborne and be blown through the cleaningsection by the blower, together with light residue material, or grainsmay remain on the sieve without falling through the sieve openings.These grain losses are respectively referred to as blow-out loss andsieve-off loss.

Present day harvesters are equipped with a sieve loss sensor arrangementmounted downstream of the cleaning section. This is usually an impactplate with a piezo-electric transducer mounted on the plate, so as toregister and count the impacts made by grains that fall onto the plate.The problem with this or any existing type of grain loss sensorarrangement is that it does not allow distinguishing between blowoutloss and sieve-off loss. As these types of losses have different causes,it is desirable to be able to distinguish between the two. This wouldallow a better control of the operational parameters that areinfluencing the loss.

Document EP-A-2022312 describes a harvester equipped with four pressuresensors underneath the upper sieve. The sensor output is used todetermine a sieve load estimator L which can be used as an indication ofthe total grain loss. No distinction is made however between blowoutloss and sieve-off loss.

SUMMARY OF THE INVENTION

The present invention is related to an agricultural harvesting vehicleas disclosed in the appended claims. The present invention is inparticular related to an agricultural harvesting vehicle, such as acombine harvester for gathering crops from a field and processing thecrops in order to separate grain kernels from residue material such asstalks and leaves. The harvesting vehicle of the invention is providedwith a cleaning section comprising a blower and at least one sieve,usually a set of an upper and lower sieve. The sieves are configured totransport a layer comprising a mixture of grain kernels and residuematerial towards an exit edge of the sieve so that kernels fall throughthe sieve's openings and residue remains on the sieve until it isejected from the sieve by crossing the exit edge. The sieve may besubject to a grain loss, consisting of a sieve-off loss and a blowoutloss, said losses being respectively due to grain kernels being ejectedtogether with the residue across the exit edge, or becoming airborne andbeing blown out of the cleaning section by the blower. In a harvesteraccording to the invention, the cleaning section is further equippedwith sensing means configured to determine whether the blowout loss orthe sieve-off loss is the highest contributor to the total grain loss.The sensing means may further be equipped with a grain loss detectorconfigured to measure the sieve off loss and at least a portion of theblowout loss. The invention is in particular related to embodimentswherein the sensing means is configured to measure a differentialpressure obtained by a suitable pressure sensing configuration or ameasurement of the blowout loss, relative to the total grain loss or tothe sieve-off loss, by an impact sensor mounted above the sieve.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1a and 1b show side and top views of the cleaning section of aharvester according to a first embodiment of the invention. FIG. 1cshows a detail of a pressure pickup according to a preferred embodiment.

FIG. 2 shows a typical graph of the total grain loss as a function ofthe pressure measured by a pressure sensor in a pressure sensingconfiguration according to the invention.

FIG. 3 illustrates the location of a reference pressure measurementabove the sieve.

FIG. 4 illustrates a preferred embodiment of a pressure sensingconfiguration according to the invention.

FIGS. 5a and 5b show side and top views of the cleaning section of aharvester according to a second embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Preferred embodiments will now be described with reference to thedrawings. The detailed description is not limiting the scope of theinvention, which is defined only by the appended claims. FIGS. 1a and 1b show a side and top view of the cleaning section of a combineharvester according to the invention. Only the cleaning section as suchis shown; the harvester as a whole is known per se in the art. Thedirection of movement of the harvester is to the left. A mixture ofgrain kernels and residue material, the latter being often referred toas ‘MOG’ (material other than grain), falls from the threshing rotors(not shown) onto a grain pan 1, from which it advances in the directionopposite the harvester's direction of movement, preferably drivenonwards by a reciprocating movement of the pan 1, towards a first sieve2, and on to the main upper sieve 3. Material falling through the firstsieve 2 is received by a second grain pan 4, which delivers it to thelower sieve 5, which extends underneath the greater portion of thesurface of the main upper sieve 3 (hereafter simply referred to as‘upper sieve’). The sieves are preferably moving the mixture onwards byway of a reciprocating movement, possibly coupled to the movement of thepan 1, in a manner that is in itself known in the art. A cleaningsection according to the invention comprises at least one sieve. Mostcleaning systems are however provided with an upper sieve 3 and a lowersieve 5, arranged with respect to each other in the manner shown in thefigures. The invention will be described with respect to the upper sieve3, but may be applied as well to the other sieves in a multiple sievecleaning section.

All sieves are preferably provided with rotatable lamellae 6 extendingtransversally with respect to the direction of travel of the mixture,and which can be rotated so as to control the size of the sieve openingsthrough which material is allowed to fall. A blower 10 is mounted so asto produce a flow of air, the air passing between the lamellae of thesieves, from the area below a sieve to the area above it. The air flowworks against the compacting of the advancing layer of MOG and grainkernels on the sieves, and at the same time this air flow blows dust andlight MOG towards the end of the cleaning section.

Underneath the lower sieve 5 is a grain slide 11 which transports grainkernels that have fallen through the sieve openings to an auger 12 whichtransports the kernels transversally with respect to the harvester'stravel direction towards a grain elevator (not shown but known to theskilled person). At the end of the lower sieve 5, a mixture of MOG and apercentage of non-sieved kernels is delivered to a MOG slide 13, leadingto a second auger 14 from where the mixture is sent back to the entranceof the cleaning section. At the end of the upper sieve 3, a mixture ofMOG and grain kernels is delivered to the MOG treatment section of theharvester, which is not shown in detail but which may be implementedaccording to known technology. This MOG treatment section usuallycomprises spreading rotors for spreading out residue material evenlyover the field behind the advancing harvester.

The stream of material that crosses the exit edge 16 of the upper sieve3 falls onto a standard grain loss detector 15. This is a sensorarrangement known in the art and arranged to measure the grain loss atthe end of the cleaning section, in other words the number of grainkernels (preferably expressed as a number of kernels per unit time) thathave failed to fall through the openings of the upper sieve 3. The grainloss detector 15 is configured to detect kernels that are lost due tothe sieve-off loss and at least a portion of the kernels that are lostdue to the blowout loss. The grain loss detector 15 may comprise animpact plate mounted parallel to the exit edge 16 of the upper sieve, sothat the mixture exiting from the upper sieve 3 falls onto the impactplate. The impact plate and cleaning section as such are configured sothat at least a percentage of the kernels that are blown out togetherwith light MOG (i.e. blowout loss) also fall onto the impact plate. Apiezo-transducer (not shown) mounted in contact with and preferably onthe bottom face of the impact plate detects the impacts made by grainkernels onto the top face of the plate, and electronic measuringequipment is provided for registering and counting these impacts. Theterm ‘(standard) grain loss detector 15’ used in the present descriptionand in the appended claims refers to a configuration that comprises oneor more sensors, for example one or more impact plates as shown in FIG.1, configured to measure the sieve loss and at least a portion of theblowout loss of a particular sieve.

As stated in the introduction, this known grain loss detection is notcapable of detecting whether the total grain loss is mainly due tosieve-off losses or to blowout loss. The present invention is related toa harvester equipped with a sensing means for detecting whether thetotal grain loss of a sieve is due mainly to blowout loss or tosieve-off loss. When a standard grain loss detector 15 is present in theharvester, said detector is part of the sensing means. According to apreferred embodiment, the sensing means is capable of determining or atleast estimating the relative contribution of the sieve-off loss and theblowout loss to the total grain loss.

In the context of this invention, the terms ‘total grain loss’,‘sieve-off loss’ and ‘blowout loss’ are defined with respect to aparticular sieve. The total grain loss of a sieve is defined as the sumof the sieve-off loss and the blowout loss related to that sieve, inother words, the total grain loss consists of a percentage of blowoutloss and a percentage of sieve-off loss, the sum of the two percentagesequaling 100%. This means that determining or estimating the total grainloss and at least one of the blowout and sieve-off loss allows todetermine whether the sieve-off loss or the blowout loss is the highestcontributor to the total grain loss. Likewise, determining the sieve-offloss and the blowout loss separately allows also determining the totalgrain loss, as well as allowing to determine which of the two is thedominant contributor.

In a first embodiment according to the invention illustrated in FIGS. 1aand 1b , a pair of pressure sensors 20 is mounted underneath the uppersieve 3, in the vicinity of the exit edge 16 of the sieve. The sensorsare mounted close to the side edges of the upper sieve 3, and downstreamof the lower sieve's exit edge 17 (‘downstream’ being used withreference to the direction of travel of a MOG/grain mixture in thecleaning section).

These pressure sensors 20 are part of a pressure sensing configurationthat measures at the sensor locations the differential air pressure,i.e. the difference between the pressure at the sensor locations and areference pressure. The reference may be the pressure of still air atatmospheric pressure. One possible setup for obtaining this pressuremeasurement is described hereafter, still with respect to FIGS. 1a , 1 band 1 c.

In the embodiment of FIG. 1, the pressure sensing configuration furthercomprises a central electronic measurement unit 21, placed centrally ata reference location, for example underneath the MOG slide 13, where thewind speed may be expected to be low. The sensors 20 themselves in thisparticular embodiment are better described as pressure pickups, as theydo not comprise the actual pressure measurement hardware, but areprimarily devices for channeling the air at the pressure that is to bemeasured, towards the measurement unit 21, which does comprise saidmeasurement hardware. A detail of one pickup 20 that is especiallysuitable for the invention is shown in FIG. 1c . The pickup is producedas a longitudinal beam-shaped element 25, with a plurality oftransversal access channels 26 provided in the body of the beam-shapedelement. The element is mounted at the side of the cleaning section sothat the channels 26 are facing the interior of the cleaning section.Inside the element, air channels 27 are formed which connect the accesschannels 26 to a longitudinal channel 28 that leads to the outletopening 29 of the pickup element. From there an air tube 30 leaves thepickup and connects it to the central measurement unit 21. The accesschannels 26 may be filled with a ceramic porous insert 31 that acts as adamping means for reducing pressure readings that are primarily due toair speed at the location of the pickup. In this way, a stablemeasurement of the static pressure at the pickup location becomespossible. The air that enters the air channels is thus at this staticpressure which is to be measured in the measurement unit 21. This may bea standard unit available from known suppliers, and capable of measuringa small differential pressure, in the order of 0-50 Pa, between thepressure at the location of the pickups 20 and the reference pressure.As seen in FIG. 1b , the measurement unit 21 in this particularembodiment thus comprises three air pressure inlets, one for each pickup20, and a third inlet 32 for the reference pressure. The referencepressure may be measured at the location of the measurement unit itself,or at another location connected to the measurement unit via an airtube. In the embodiment shown, the reference location is the location ofthe measurement unit itself. A suitable type of measurement unit isavailable from the supplier SensorTechnics. An electric cable 33 exitsthe measurement unit, carrying a signal that is proportional to themeasured differential pressure to an electronic processing device, notshown in the drawings and known per se in the art.

The differential pressure obtained from each pressure pickup 20 may beevaluated separately or the two signals may be combined to a singlesignal, e.g. by taking the average or the sum of the two. FIG. 2 shows atypical measurement curve of the total grain loss as a function of theoutput of one of the pressure pickups 20, i.e. the differential pressureat the measurement location with respect to the reference. The totalgrain loss is measured by the standard grain loss detector 15 andexpressed for example as the number of kernel impacts on the impactplate of the grain loss detector 15 per unit time. Even when the grainloss detector 15 measures only a portion of the blowout loss, the outputof the grain loss detector can be used for determining the curve of FIG.2, as this output will in any case be directly related to the actualtotal grain loss.

As seen in FIG. 2, the curve exhibits a minimum. Excessive grain loss isthus related to either a pressure reading that is too low or too high. Ahigh pressure indicates that the grain loss is mainly due to sieve-offlosses: a dense layer of the MOG/grain mixture is forming on the sieve,causing an increase of pressure underneath the sieve, as air from theblower 10 fails to pass through the sieve openings. The dense layercarries with it an amount of grain kernels that fail to reach the bottomof the layer and which are therefore evacuated together with the MOG.When the pressure is too low, this indicates that the air flowingthrough the sieve openings meets insufficient resistance from theMOG/grain layer, so that grain kernels become airborne and are blown outbeyond the exit edge 16 of the sieve 3. In other words, the grain lossis mainly due to blowout loss. The pressure sensing configuration in aharvester of the invention is configured in such a way that the curverelating the total grain loss to the measured pressure exhibits aclearly defined minimum, in the manner shown in FIG. 2. This can beachieved by a number of factors, one of which being the choice of asuitable location of the sensor pickups 20 in the direction of travel ofthe mixture within the cleaning section. Measuring too much upstreamwill generally result in high pressure readings regardless of the grainloss, given that the MOG/grain layer is thicker when it begins itsadvance on the sieve. Measuring too far downstream will result in lowpressure readings regardless of the grain loss. Another aspect is thetype of pressure measurement, which is preferably the above-describeddifferential pressure measurement given that this measurement is verysensitive to changes in the conditions that determine the grain loss.Also the type of sensors and pressure pickups and the location of thepressure and reference pressure measurements may be of influence.Preferred embodiments of the pressure pickup 20 and reference unit 21have been described above. Further embodiments, particularly of thelocation of the reference measurement and the number of said referencesto be applied, will be described hereafter.

When the grain loss curve of FIG. 2 is established on a harvestingmachine by performing a number of tests in various circumstances, thiscurve may be used to determine whether an excessive grain loss is duemainly to blowout loss or to sieve-off loss. Around the minimum, a zone35 may be defined by defining critical levels L₁ and L₂ of the totalgrain loss. Alternatively, a single critical level may be defined. Thezone 34 is situated between a lower and a higher pressure level p₁/p₂respectively and represents a total grain loss that is acceptable, i.e.lower than either of the levels L₁ and L₂. When the total grain loss, asmeasured by the grain loss detector 15, exceeds at least one of thecritical levels, the pressure reading indicates whether the loss ismainly due to blowout loss (when p<p₁) or to sieve-off loss (when p>p₂).Appropriate measures can thus be taken to mitigate grain loss, whereinsaid measures are different depending on whether the loss originates inblowout loss or sieve-off loss. For example, when blowout losses aredominating, the blower speed may be reduced and/or the sieve openingsdecreased. When sieve-off losses dominate, the blower speed may beincreased and/or the sieve openings increased.

The above method of determining—by comparing the pressure reading withpredefined fixed levels p₁ and p₂—whether or not an excessive totalgrain loss is mainly due to blowout loss or sieve-off loss, may not bepossible in all circumstances. The values of p₁ and p₂ may for exampledepend on weather conditions and crop type or humidity. When p₁ and p₂are not clearly known, the differential pressure that is measured whenthe total grain loss exceeds a critical value may be compared to asingle value, for example a value of the differential pressuremeasurement or an average of differential pressure measurements obtainedwhen the grain loss is below the critical value(s). When thedifferential pressure (measured when the total loss is above critical)is below the single value, the loss is concluded to be mainly due toblowout loss. When it is above the single value, the loss is concludedto be mainly due to sieve-off loss.

According to an embodiment, the sensing means is capable not only ofestimating whether the total grain loss is due mainly to blowout loss orto sieve-off loss, but equally to determine or at least estimate on thebasis of the output of the pressure sensing configuration 20/21 and theoutput of the grain loss detector 15, the relative contribution of theblowout loss and of the sieve-off loss to the total grain loss. Thesecontributions could for example be derived from the location of themeasurement point on the curve of FIG. 2, provided that the curve isknown to be representative for the actual conditions in which theharvester is operating. A measurement point p_(m) for example (see FIG.2) indicates a point where the total grain loss is lower than thecritical values, but where clearly blowout loss contributes more to thetotal grain loss than sieve-off loss. An estimation of the percentage ofblow-off loss and sieve-off loss can be made from the lengths of thelines p_(m)p_(b) and p_(a)p_(m) relative to the line p_(a)p_(b). Therelative contributions can be used for fine-tuning the cleaningarrangement, even when the total grain loss is below the criticalvalue(s).

When the curve of FIG. 2 is reliably known, the standard grain losssensor 15 is not strictly required and may be omitted. The measuredpressure difference may then simply be compared to the limit values p1and p2 in order to determine whether the total grain loss is excessiveor not. When p<p1 it is concluded that the total grain loss is excessiveand due mainly to blowout loss, and when p>p2 it is concluded that thegrain loss is excessive and mainly due to sieve-off loss. When p isbetween p1 and p2, the total grain loss may be concluded to beacceptable. When the estimation of the contributions p_(a)p_(m) andp_(m)p_(b) of the sieve-off loss and the blowout loss is reliable, thetotal grain loss (below or above the limit values L₁/L₂) can bedetermined as the sum of the two contributions. As an alternative or inaddition to working with the limit values p1 and p2 for the differentialpressure, the differential pressure measurement(s) may be compared tothe minimum value p_(min) (see FIG. 2), with blowout loss being the maincontributor to the total grain loss when p<p_(min) and sieve-off lossbeing the main contributor when p>p_(min). As stated above, thereference measurement 21 can be done at other locations instead of theone shown in the drawings. Also, a plurality of reference locations maybe applied, for example one for each pressure measurement. According toone embodiment, the reference location is a location outside thecleaning section, where the wind speed is minimal. According to onespecific embodiment, the reference location is a location where the windspeed is similar to the measurement location. The feature ‘wind speedsimilar to the measurement location’ is a physical feature of theharvester, and depends on the structural characteristics of the vehicleand the area where the various sensors are installed. It can be verifiedby doing wind speed measurements at various locations for example. Thefact that the influence of wind on the measurement and on the referenceis similar, results in a differential measurement wherein the influenceof the wind is minimised.

Preferred reference locations that face similar wind speed conditions asthe measurement location(s) are found above the upper sieve 3, asillustrated in FIG. 3. The reference location is illustrated by thelocation of the measurement unit 21, even though it is not required thatthis unit is physically present at this location. An air tube couldconnect a pressure pickup 20 that is mounted at the reference location,to the measurement unit 21 that is mounted elsewhere and connected tothe pressure pickup via an air tube. Suitable physical attachment meansare provided for attaching the unit 21 and/or a pressure pickup 20 abovethe sieve and attached for example to the ceiling of the cleaningsection.

The exact reference location yielding the minimum wind speed influencemay depend on structural details of the cleaning section, as well as onthe type of sensors or pressure pickups used. One preferred setup isillustrated in FIG. 4, which shows one side of the upper sieve 3. Alsovisible is the sidewall 35 of the cleaning section. A pressure pickup 20is mounted underneath the upper sieve 3 as in the embodiment of FIG. 1.A second pick up 20′ is mounted above the upper sieve 3. Preferably, thelower pickup 20 and the upper pickup 20′ are of the filter block typeshown in FIG. 1c . Preferably, these filter blocks are incorporated intothe sidewall 35 of the cleaning section, i.e. the inlet sections of thefilter elements 31 in the filter blocks are flush with the sidewall, asillustrated in FIG. 4. The filter block 20′ mounted above the sievedefines the location where the reference measurement is done. The upperand lower filter block 20/20′ are connected via air tubes 36 to ameasurement unit 21 that may for example be mounted on the back side ofthe side wall 35. On the opposite side of the sieve 3 (not shown),another pair of pressure pickups 20/20′ is mounted in the same way,connected via air tubes to another measurement unit 21, i.e. a separatemeasurement unit 21 is provided on each side of the sieve 3. Thisensures reliability of the measurement on both sides of the sieve, interms of the minimization of the influence of wind, as explained above.The pickups 20/20′ could alternatively be connected to the sieve itself,provided that the sieve is structurally suitable for mounting thepickups at the same location as illustrated in FIG. 4, with respect tothe sieve's supporting surface.

According to a second embodiment, illustrated in FIG. 5, the cleaningsection is equipped with one or more impact sensors 37 mounted above theupper sieve 3, in the vicinity of the exit edge 16 of the sieve, eitheraligned with this exit edge or slightly upstream or downstream of theexit edge. These impact sensor or sensors are mounted in a suitablelocation for detecting the presence of grain kernels that are airborneat the sensor location, and that are therefore necessarily contributingto the blowout loss. The number of impacts detected per unit time is ameasure of the blowout loss as such. Hence these sensors 37 arehereafter referred to as blowout sensors. In the embodiment, of FIG. 5,the blowout sensor or sensors 37 are present in addition to the standardgrain loss detector 15 mounted at the end of the upper sieve 3.According to one embodiment, the grain loss detector 15 is configured toactually detect essentially all of the kernels that are lost by theblowout loss effect. In other words, the kernels that are detected bythe blowout sensor(s) 37 eventually fall onto the grain loss detector 15as well, so the combination of the two signals (from blowout sensor(s)on the one hand and standard detector 15 on the other) allows todetermine whether an excessive grain loss is due primarily to blowoutlosses or to sieve-off losses. This can be done by monitoring the totalgrain loss with the standard loss detector 15, and determining thecontribution of the blowout loss to this total grain loss on the basisof the output of the blowout sensor or sensors 37. Possibly, thisdetermination is done only when the total grain loss exceeds apredetermined critical value. The output of the blowout sensor(s) 37 andof the standard detector 15 may be obtained as a number of kernelimpacts per unit time. Taking into account the surface area of theimpact plates of the blowout sensor(s) and the standard detector 15,with respect to the width of the cleaning section, the results may becalculated to obtain the blowout loss and the total grain loss in termsof a number of kernels per unit time. It is then verified whether theblowout loss represents more or less than 50% of the total grain loss,at which point appropriate control action can be taken (preferably onlywhen the total grain loss exceeds a predetermined critical value).

In another embodiment comprising the blowout sensor(s) 37, the standardgrain loss detector 15 measures the sieve-off loss and only a percentageof the blowout loss, for example because the impact plate is notpositioned in a manner that it is assured to receive all of the kernelsblown out of the cleaning section. In this case, the output of the grainloss detector 15 cannot be used in the above manner to numericallydetermine or estimate the contribution of the blowout loss to the totalgrain loss. However, the blowout sensor still delivers an estimation ofthe blowout loss as such, and in most circumstances, for example whenthe difference between the output of the blowout sensor(s) 37 and thegrain loss sensor 15 is very high or very low, the outputs will stillallow to determine whether the blowout loss or the sieve-off loss is thehighest contributor to the total grain loss.

In another embodiment, the harvester is equipped with the blowoutsensor(s) 37 and with a detector that measures essentially only thesieve-off loss. The latter can be an impact plate placed downstream ofthe sieve, but positioned in such a way that the kernels that are blownout of the cleaning section do not impact said plate. This may furtherbe achieved by designing the cleaning section in such a way that theblown-out kernels are guided away from this impact plate. In thisembodiment, the blowout sensor(s) 37 and the sieve-off detector provideseparate measurements of the blowout loss and the sieve-off lossrespectively, which equally allows determining which of the two is thelargest contributor to the total grain loss. In the latter embodiment,the harvester does not comprise a ‘standard grain loss detector’ asdefined above, as it comprises a means to determine the blowout loss andthe sieve-off loss separately.

The advantage of the embodiments comprising one or more blowout sensors37 is that the contributions of the blowout loss and sieve off loss assuch or at least estimations thereof are readily available or can beeasily calculated, so that it is easier to perform fine-tuning of thecleaning section on the basis of the output of the sensingconfiguration, even when the total grain loss is below a critical value.

One preferred location for a blowout sensor 37 is shown in the top viewshown in FIG. 5b . In this embodiment the sensor is mounted on a sidewall 35 of the cleaning section. The sensor is advantageously producedin the form of an impact plate 38 that is vertically mounted against theside wall 35, with the face of the plate perpendicular to the directionof travel of the MOG/grain mixture in the cleaning section. Apiezo-transducer 39 is connected at the back of the plate 38 in order toregister the impacts and send related signals via a cable 40 to aprocessing device, in the manner that is known per se for the grain lossdetector 15 described above. One blowout sensor 37 of this type maysuffice but a second sensor may be placed on the opposite side of thesieve 3. The combined signals of these two sensors may provide a moreaccurate estimation of the blowout loss in the case of a MOG/grainmixture layer that is unevenly spread across the width of the uppersieve 3. Another possibility is to mount one impact plate horizontallyabove the centre of the sieve, possibly even extending over the wholewidth of the sieve.

In any of the above described embodiments, the harvester furthercomprises a means for determining whether blowout or sieve-off lossesdominate the total grain loss and (if possible) how much each iscontributing. These means may comprise any suitable signal acquisitionand treatment equipment, configured to compare measured parameters (e.g.differential pressure measurements or number of impacts on the blowoutsensor 37) to predefined limit values and to calculate and deliverresults to a controller configured to control the grain loss by actingon one or more machine parameters (see further) and possibly to asuitable output device such as a computer screen.

Any of the sensing configurations described above with respect to theupper sieve 3 may be applied as well to the lower sieve 5 or to anyadditional sieve present in the cleaning section. As stated, the terms‘grain loss’, ‘sieve-off loss’ and blowout loss' are to be understood inrelation to a particular sieve, namely as the amount of grain kernels ina grain/MOG mixture advancing on the sieve, that fail to fall throughthe sieve openings, and are thus carried off beyond the sieve's exitedge, either by being blown out, or by remaining in the grain/MOG layer.In the cleaning section of FIG. 1a , the ‘grain loss’ of the lower sieve5 is not a grain loss of the harvester as such, given that the majorityof the lower sieve's loss is recycled via the MOG slide 13 and returnauger 14. The sensing arrangement of the invention, when applied to thelower sieve 5, thus provides a way of monitoring and controlling theamount of grain returned to the start of the cleaning section. This isuseful as it allows avoiding blockages in the return path due toexcessive ‘losses’ of the lower sieve 5.

Regardless of whether pressure sensors or impact sensors are used, theoutput of a sensing configuration according to the invention may be usedas input to a process for controlling operational parameters of theharvester. Said output may be a signal that signifies simply thatexcessive grain loss is taking place, the signal having a first valuewhen the grain loss is due mainly to blowout loss (e.g. p<p1) and asecond value when the grain loss is mainly due to sieve-off loss (e.g.p>p2). In addition, the output could be more specific and specify anestimated contribution (e.g. a percentage) of blowout loss and ofsieve-off loss to the total grain loss. The main parameters that have animpact on the grain loss are the blower speed and the sieve openings ofthe sieve, the latter being controlled by controlling the position ofthe rotatable lamellae 6. For example, when the blowout loss becomes tooimportant, this may be remedied primarily by decreasing the blower speedand/or by decreasing the sieve openings of the sieve. When the sieve-offloss becomes too important, this may be remedied by increasing theblower speed and/or by increasing the sieve openings. It is cleartherefore that different actions are required when either the blowoutloss or the sieve-off loss is the dominant contributor to the totalgrain loss. The present invention allows determining which actions arethe most appropriate actions to be taken in order to minimize the lossat any time during operation of the harvester. The parameters that arecontrolled are not necessarily limited to the blower speed and uppersieve openings, but may include other machine parameters, e.g. the speedof the reciprocating movement of the sieves. The precise controlalgorithm that may be used on the basis of the measurements obtainedfrom the pressure sensing configuration 20/21 or the blowout sensor(s)35 combined with the output of the standard grain loss sensor 15 is nota part of this specification and may involve known procedures andschemes, similar for example to the fuzzy logic approach disclosed inEP2022312.

The method for controlling the grain loss of a sieve in the cleaningsection of a harvesting vehicle according to the invention comprises thesteps of:

determining on the basis of the output of the sensing means, the valueof a parameter related to the blowout loss and the sieve-off loss,

determining on the basis of the measured parameter whether the grainloss is mainly due to blowout loss or to sieve off loss, by comparingthe measured parameter to one or more limit values.

In the case of the differential pressure embodiments, the parameter maybe the differential pressure at one measurement location or an averageor sum of differential pressures at several measurement locations. Thelimit values may be the values p₁+p₂ and/or p_(min). In the blowoutsensor embodiments, the parameter may be the ratio of the output of theblowout sensor 37 to the output of the standard grain loss sensor 15configured to measure the total grain loss, said ratio being compared tothe limit value of 50%, or the ratio of the output of the blowout sensor37 to the output of a sensor configured to measure only the sieve-offloss, the limit value being 1.

1. A cleaning section of an agricultural harvesting vehicle the cleaningsection comprising: a blower; at least one sieve having sieve openings,the blower being configured to produce an air flow through the sieveopenings from an area below the at least one sieve to an area above theat least one sieve, the at least one sieve configured to transport alayer comprising a mixture of grain kernels and residue material towardsan exit edge of the at least one sieve so that kernels fall through theopenings of the at least one sieve and residue remains on the at leastone sieve until it is ejected from the at least one sieve by crossingthe exit edge, the at least one sieve being be subject to a total grainloss, consisting of a sieve-off loss and a blowout loss, the lossesbeing respectively due to grain kernels being ejected together with theresidue across the exit edge, or becoming airborne and being blown overthe exit edge by the blower; and a sensing system comprising a sensorconfigured to provide an output, the sensing system configured to:determine, based on the output of the sensor, a parameter related to theblowout loss and the sieve-off loss, and determine, based on theparameter, whether the blowout loss or the sieve-off loss is a highestcontributor to the total grain loss.
 2. The cleaning section accordingto claim 1, wherein the sensing system further comprises a grain lossdetector, configured to measure a grain loss consisting of the sieve-offloss and at least a portion of the blowout loss.
 3. The cleaning sectionaccording to claim 1, wherein the sensor comprises a pressure sensingconfiguration, configured to measure a pressure difference between anair pressure at a measurement location underneath the at least one sieveand an air pressure at a reference location.
 4. The cleaning sectionaccording to claim 3, wherein the reference location is a locationoutside the cleaning section.
 5. The cleaning section according to claim3, wherein the reference location is a location above the at least onesieve.
 6. The cleaning section according to claim 3, wherein the sensingsystem further comprises one or more measurement units, wherein thepressure sensing configuration comprises one or more pressure pickups,connected via external air tubes to the one or more measurement units,wherein the one or more pickups are mounted at the measurement locationor at the reference location, the one or more pickups comprising one ormore access channels oriented transversally with respect to a transportdirection of the mixture of grain kernels and residue material, the oneor more access channels being interconnected through respective one ormore internal air tubes in an interior of the pickup, the one or moreinternal air tubes being connected to one or more external air tubesconnecting the one or more pickups to the one or more measurement units.7. The cleaning section according to claim 6, wherein each of the one ormore access channels is at least partially filled with a porous insert.8. The cleaning section according to claim 6, wherein the at least onesieve is mounted between sidewalls of the cleaning section, and whereinthe sensor comprises: a first pickup mounted at a first locationunderneath the at least one sieve, a second pickup mounted at a secondlocation above the at least one sieve, and a measurement unit,configured to measure the pressure difference between the first andsecond locations, wherein the first and second pickups are connected viaair tubes to the measurement unit.
 9. The cleaning section according toclaim 8, wherein each of the first and second pickups is attached to oneof the sidewalls.
 10. The cleaning section according to claim 6, whereinthe one or more pressure pickups comprise a plurality of pressurepickups, and wherein the one or more measurement units comprises acentral measurement unit for the plurality of pressure pickups.
 11. Thecleaning section according to claim 10, wherein the one or more pickupscomprises two pickups mounted on opposite sides of the at least onesieve, near the exit edge of the at least one sieve.
 12. The cleaningsection according to claim 3, wherein the reference location is alocation where wind speed conditions are similar to the measurementlocation.
 13. The cleaning section according to claim 1, wherein thesensing system comprises: one or more impact sensors mounted above theat least one sieve, so as to register impacts made by grain kernels thatare contributing to the blowout loss, and a grain loss detector,configured to measure a grain loss consisting of the sieve-off loss andat least a portion of the blowout loss.
 14. The cleaning sectionaccording to claim 1, wherein the sensing system further comprises: oneor more impact sensors mounted above the at least one sieve, so as toregister impacts made by grain kernels that are contributing to theblowout loss, and a detector configured to measure the sieve-off loss.15. The cleaning section according to claim 13, wherein the one or moreimpact sensors comprise: an impact plate mounted on a sidewall of thecleaning section, in the vicinity of the exit edge of the at least onesieve, the impact plate facing a transport direction of the mixture ofgrain kernels and residue material on the at least one sieve, and animpact transducer mounted on the impact plate.
 16. A method forcontrolling a cleaning section of an agricultural harvester, thecleaning section comprising a blower, and at least one sieve havingsieve openings, the blower being configured to produce an air flowthrough the sieve openings from an area below the at least one sieve toan area above the at least one at least one sieve, the at least onesieve configured to transport a layer comprising a mixture of grainkernels and residue material towards an exit edge of the at least onesieve so that kernels fall through the openings of the at least onesieve and residue remains on the at least one sieve until it is ejectedfrom the at least one sieve by crossing the exit edge, the at least onesieve being be subject to a total grain loss, consisting of a sieve-offloss and a blowout loss, the losses being respectively due to grainkernels being ejected together with the residue across the exit edge, orbecoming airborne and being blown over the exit edge by the blower, thecleaning section further comprising a sensing system comprising a sensorconfigure to provide an output, the method comprising the steps of:determining, based on the output of the sensor, parameter related to theblowout loss and the sieve-off loss, determining, based on theparameter, whether the total grain loss is mainly due to the blowoutloss or to the sieve-off loss, by comparing the parameter to one or morelimit values, and if required, acting on one or more operationalconditions of the cleaning section in order to control the total grainloss.
 17. The method according to claim 16, further comprising the stepof determining or at least estimating contributions of the blowout lossand the sieve-off loss to the total grain loss.
 18. The method accordingto claim 16, wherein the sensor comprises a pressure sensingconfiguration, configured to measure a pressure difference between anair pressure at a measurement location underneath the at least one sieveand an air pressure at a reference location, wherein the parameter isthe pressure difference, the method further comprising steps of:determining that the grain loss is mainly due to blowout loss if themeasured pressure difference is below a first limit value, and determinethat the grain loss is mainly due to sieve-off loss if the measuredpressure difference is above a second limit value.